The latest model, the OH-58D Kiowa Warrior, is primarily operated in an armed reconnaissance role in support of ground troops. The OH-58 has been exported to Austria, Canada, the Dominican Republic, Taiwan, and Saudi Arabia. It has also been produced under license in Australia.

Bell developed the D-250 design into the Model 206 aircraft, redesignated as YOH-4A in 1962, and produced five prototype aircraft for the Army's test and evaluation phase. The first prototype flew on 8 December 1962.[7] The YOH-4A also became known as the Ugly Duckling in comparison to the other contending aircraft.[7] Following a flyoff of the Bell, Hughes and Fairchild-Hiller prototypes, the Hughes OH-6 Cayuse was selected in May 1965.[8]

When the YOH-4A was rejected by the Army, Bell went about solving the problem of marketing the aircraft. In addition to the image problem, the helicopter lacked cargo space and only provided cramped quarters for the planned three passengers in the back. The solution was a fuselage redesigned to be more sleek and aesthetic, adding 16 cubic feet (0.45 m3) of cargo space in the process.[9] The redesigned aircraft was designated as the Model 206A, and Bell President Edwin J. Ducayet named it the JetRanger denoting an evolution from the popular Model 47J Ranger.

YOH-4A LOH in flight.

In 1967, the Army reopened the LOH competition for bids because Hughes Tool Co. Aircraft Division could not meet the contractual production demands.[10] Bell resubmitted for the program using the Bell 206A.[4] Fairchild-Hiller failed to resubmit their bid with the YOH-5A, which they had successfully marketed as the FH-1100.[11] In the end, Bell underbid Hughes to win the contract and the Bell 206A was designated as the OH-58A. Following the U.S. Army's naming convention for helicopters, the OH-58A was named Kiowa in honor of the Native American tribe.[12]

In the 1970s, the U.S. Army began evaluating the need to improve the capabilities of their scout aircraft. The OH-58A lacked the power for operations in areas that exposed the aircraft to high altitude and hot temperatures, areas where the ability to acquire targets was a critical deficiency in the tactical warfare capabilities of Army aviation.[13]

The power shortcoming caused other issues as the Army anticipated the AH-64A's replacement of the venerable AH-1 in the Attack battalions of the Army. The Army began shopping the idea of an Aerial Scout Program to industry as a prototype exercise to stimulate the development of advanced technological capabilities for night vision and precision navigation equipment.[13] The stated goals of the program included prototypes that would:

...possess an extended target acquisition range capability by means of a long-range stabilized optical subsystem for the observer, improved position location through use of a computerized navigation system, improved survivability by reducing aural, visual, radar, and infrared signatures, and an improved flight performance capability derived from a larger engine to provide compatibility with attack helicopters.[13]

In early March 1974, the Army created a special task force at Fort Knox to develop the system requirements for the Aerial Scout Helicopter program,[14] and in 1975 the task force had formulated the requirements for the Advanced Scout Helicopter (ASH) program. The requirements were formulated around an aircraft capable of performing in day, night, and adverse weather and compatible with all the advanced weapons systems planned for development and fielding into the 1980s. The program was approved by the System Acquisition Review Council and the Army prepared for competitive development to begin the next year.[15] However, as the Army tried to get the program off the ground, Congress declined to provide funding for it in the fiscal year 1977 budget and the ASH Project Manager's Office (PM-ASH) was closed on 30 September 1976.[16]

While no development occurred during the next few years, the program survived as a requirement without funding. On 30 November 1979, the decision was made to defer development of an advanced scout helicopter in favor of pursuing modification of existing airframes in the inventory as a near term scout helicopter (NTSH) option. The development of a mast-mounted sight would be the primary focus to improve the aircraft's ability to perform reconnaissance, surveillance, and target acquisition missions while remaining hidden behind trees and terrain. Both the UH-1 and the OH-58 were evaluated as NTSH candidates, but the UH-1 was dropped from consideration due to its larger size and ease of detection. The OH-58, on the other hand demonstrated a dramatic reduction in detectability with a Mast-Mounted Sight (MMS).

On 10 July 1980, the Army decided that the NTSH would be a competitive modification program based on developments in the commercial helicopter industry, particularly Hughes Helicopters development of the Hughes 500D which provided significant improvements over the OH-6.[17]

The Army's decision to acquire the NTSH resulted in the "Army Helicopter Improvement Program (AHIP)". Both Bell Helicopter and Hughes Helicopters redesigned their scout aircraft to compete for the contract. Bell offered a more robust version of the OH-58 in their model 406 aircraft,[18] and Hughes offered an upgraded version of the OH-6. On 21 September 1981, Bell Helicopter Textron was awarded a development contract.[19][20] The first prototype flew on 6 October 1983,[2] and the aircraft entered service in 1985 as the OH-58D.[21]

Initially intended for attack, cavalry and artillery roles, the Army only approved a low initial production level and confined the role of the OH-58D to field artillery observation. The Army also directed that a follow-on test be conducted to further evaluate the aircraft due to perceived deficiencies. On 1 April 1986, the Army formed a task force at Fort Rucker, Alabama, to remedy deficiencies in the AHIP.[21] In 1988, the Army had planned to discontinue the OH-58D and focus on the LHX; however, Congress approved $138 million to expand the program, calling for the AHIP to operate with the Apache as a hunter/killer team; the AHIP would locate targets and the Apache would destroy them in a throwback to the traditional OH-58/AH-1 relationship.[22]

The Secretary of the Army directed instead that the aircraft's armament systems be upgraded, based on experience with Task Force 118's performance operating armed OH-58D helicopters in the Persian Gulf in support of Operation Prime Chance, and that the aircraft be used primarily for scouting and armed reconnaissance.[23] The armed aircraft would be known as the OH-58D Kiowa Warrior, denoting its new armed configuration. Beginning with the production of the 202nd aircraft (s/n 89-0112) in May 1991, all remaining OH-58D aircraft were produced in the Kiowa Warrior configuration. In January 1992, Bell Helicopter received its first retrofit contract to convert all remaining OH-58D Kiowa helicopters to the Kiowa Warrior configuration.[2]

The OH-58D introduced the most distinctive feature of the Kiowa family — the Mast Mounted Sight (MMS), which resembles a beach ball perched above the rotor system. The MMS by Ball Aerospace & Technologies has a gyro-stabilized platform containing a TeleVision System (TVS), a Thermal Imaging System (TIS), and a Laser Range Finder/Designator (LRF/D). These new features gave the aircraft the additional mission capability of target acquisition and laser designation in both day or night, and in limited-visibility and adverse weather.[citation needed]

The Mast Mounted Sight system was developed by the McDonnell Douglas Corp. in Huntington Beach, CA. Production took place primarily at facilities in Monrovia, CA. As a result of a merger with Boeing, and a later sale of the business unit, the program is currently owned and managed by DRS Technologies, with engineering support based in Cypress, CA, and production support taking place in Melbourne, FL.[24]

One distinctive feature of operational OH-58s are the knife-like extensions above and below the cockpit which are part of the passive Wire Strike Protection System. It can protect 90% of the frontal area of the helicopter from wire strikes that can be encountered at low altitudes by directing wires to the upper or lower blades before they can entangle the rotor blade or landing skids. The OH-58 was the first helicopter to test this system, after which the system was adopted by the US Army for the OH-58 and most of their other helicopters.[25]

Major General John Norton, commanding general of the Army Aviation Materiel Command (AMCOM),[26] received the first OH-58A Kiowa at a ceremony at Bell Helicopter's Fort Worth plant in May 1969. Two months later, on 17 August 1969, the first production OH-58A Kiowa helicopters were arriving in Vietnam,[27] accompanied by a New Equipment Training Team (NETT) from the Army and Bell Helicopters.[28] Although the Kiowa production contract replaced the LOH contract with Hughes, the OH-58A did not automatically replace the OH-6A in operation. Subsequently, the Kiowa and the Cayuse would continue operating in the same theater until the end of the war.

On 27 March 1970, an OH-58A Kiowa (s/n 68-16785) was shot down over Vietnam, one of the first OH-58A losses of the war. The pilot, Warrant Officer Ralph Quick, Jr., was flying Lieutenant Colonel Joseph Benoski, Jr. as an artillery spotter. After completing a battle damage assessment for a previous fire mission, the aircraft was damaged by .51 cal (13 mm) machine gun fire and crashed, killing both crew members. Approximately 45 OH-58A helicopters were destroyed during the Vietnam War due to combat losses and accidents.[29] One of the last combat losses was of an OH-58A (s/n 68-16888) from A Troop, 3-17th Cavalry, flown by First Lieutenant Thomas Knuckey. On 27 May 1971, Lieutenant Knuckey was also flying a battle damage assessment mission when his aircraft came under machine gun fire and exploded. Knuckey and his observer, Sergeant Philip Taylor, both died in the explosion.[30]

In early 1988, it was decided that armed OH-58D (AHIP) helicopters from the 118th Aviation Task Force would be phased in to replace the SEABAT (AH-6/MH-6) teams of Task Force 160th to carry out Operation Prime Chance, the escort of oil tankers during the Iran–Iraq War. On 24 February 1988, two AHIP helicopters reported to the Mobile Sea Base Wimbrown VII, and the helicopter team ("SEABAT" team after their callsign) stationed on the barge returned to the United States. For the next few months, the AHIP helicopters on the Wimbrown VII shared patrol duties with the SEABAT team on the Hercules. Coordination was difficult, but despite frequent requests from TF-160, the SEABAT team on the Hercules was not replaced by an AHIP detachment until June 1988.[31] The OH-58D helicopter crews involved in the operation received deck landing and underwater survival training from the Navy.

In November 1988, the number of OH-58D helicopters that supported Task Force 118 was reduced. However, the aircraft continued to operate from the Navy's Mobile Sea Base Hercules, the frigate Underwood, and the destroyer Conolly. OH-58D operations primarily entailed reconnaissance flights at night, and depending on maintenance requirements and ship scheduling, Army helicopters usually rotated from the mobile sea base and other combatant ships to a land base every seven to fourteen days. On 18 September 1989, an OH-58D crashed during night gunnery practice and sank, but with no loss of personnel. When the Mobile Sea Base Hercules was deactivated in September 1989, all but five OH-58D helicopters redeployed to the continental United States.[32]

In 1989, Congress mandated that the Army National Guard would take part in the country's War on Drugs, enabling them to aid federal, state and local law enforcement agencies with "special congressional entitlements". In response, the Army National Guard Bureau created the Reconnaissance and Aerial Interdiction Detachments (RAID) in 1992, consisting of aviation units in 31 states with 76 specially modified OH-58A helicopters to assume the reconnaissance/interdiction role in the fight against illegal drugs. During 1994, 24 states conducted more than 1,200 aerial counterdrug reconnaissance and interdiction missions, conducting many of these missions at night.[33] Eventually, the program was expanded to cover 32 states and consisting of 116 aircraft, including dedicated training aircraft at the Western Army Aviation Training Site (WAATS) in Marana, Arizona.[34]

The RAID program’s mission has now been expanded to include the war against terrorism and supporting U.S. Border Patrol activities in support of homeland defense. The National Guard RAID units' Area of Operation (AO) is the only one in the Department of Defense that is wholly contained within the borders of the United States.[34]

On 17 December 1994, Army Chief Warrant Officers (CWO) David Hilemon and Bobby Hall left Camp Page, South Korea on a routine training mission along the Demilitarized Zone (DMZ). Their flight was intended to be to a point known as Checkpoint 84, south of the DMZ "no-fly zone", but the OH-58C Kiowa strayed nearly four miles (6.4 km) into the Kangwon Province, inside North Korean airspace, due to errors in navigating the snow-covered, rugged terrain. The helicopter was shot down by North Korean troops and CWO Hilemon was killed. CWO Hall was held captive and the North Korean government insisted that the crew had been spying. Five days of negotiations resulted in the North Koreans turning over Hilemon's body to U.S. authorities. The negotiations failed to secure Hall's immediate release. After 13 days in captivity, Hall was freed on 30 December, uninjured.[36][37]

The United States Army has employed the OH-58D during Operation Iraqi Freedom in Iraq and Operation Enduring Freedom in Afghanistan.[38][39] Due to combat and accidents, over 35 airframes have been lost, with 35 pilots killed.[40] Their presence has also been anecdotally credited with saving lives, having been used to rescue wounded despite their small size.[41] In Iraq, OH-58Ds flew 72 hours per month, while in Afghanistan, they flew 80 hours per month.[42] In 2013, Bell stated that the OH-58 had 820,000 combat hours, and 90% mission capable rate.[43]

The first attempt to replace the OH-58 was the RAH-66 Comanche of the Light Helicopter Experimental program, which was cancelled in 2004. Airframe age and losses led to the Armed Reconnaissance Helicopter program to procure a new aircraft, the Bell ARH-70, which was later cancelled in 2008 due to cost overruns. The third replacement effort for the OH-58 was the Armed Aerial Scout program.[44] Due to uncertainty in the AAS program and fiscal restraints, planned retirement of the OH-58F Kiowa has been extended from 2025 to 2036.[45] The Kiowa's role as a scout aircraft is being supplemented by tactical unmanned aerial vehicles, the two platforms often act in conjunction to provide reconnaissance to expose crews to less risk. The OH-58F has the ability to control UAVs directly to safely perform scout missions.[42] In 2011, the Kiowa was scheduled to be replaced by the light version of the Future Vertical Lift aircraft in the 2030s.[46]

As of December 2013, the U.S. Army has 338 Kiowas in its active-duty force and 30 in the Army National Guard. The Army is considering retiring the Kiowa as part of a wider restructuring to cut costs and reduce the various types of helicopters in service. The Analysis of Alternatives (AoA) for the AAS program found that the Kiowa operating alongside RQ-7 Shadow UAVs was the most affordable and capable solution; it also said that the AH-64E Apache Guardian was the most capable "immediate" solution for the scout helicopter role. It is proposed that all OH-58s be divested and all National Guard and Army Reserve Apaches would be transferred to the active Army to serve as scouts. The Apache costs 50 percent more than the Kiowa to operate and requires more maintenance; studies showed that if the Apache had been used in place of the Kiowa in Iraq and Afghanistan, total operating costs would have been $4 billion greater, but would save $1 billion per year in operating and sustainment costs. UH-60 Black Hawks would be transferred from the active fleet to reserve and Guard units. The proposal aims to retire older helicopters to save money and retain those with the greatest capabilities.[47] The 2010 AoA that found that Apaches teamed with UAVs was the optimal choice; with a reduced service size a total of 698 Apaches could fill the role. Funds for Apache upgrades would be released from the Kiowa's termination.[48] Media expects the OH-58s to go to foreign military rather than civilian operators due higher operating cost.[49]

The Army will place 26 out of 335 OH-58Ds in non-flyable storage during 2014. In anticipation of divesting the Kiowa, the Army is looking to see if other military branches, government agencies, and foreign customers would be interested in buying the aircraft. The Kiowas are considered in a good price range for foreign countries with limited resources. Bell has not yet agreed to support the helicopters if sold overseas. In November 2014 Croatia sent a letter of intent for the acquisition of 16 OH-58Ds.[50][51] As of 2015[update], the Army has divested 33 OH-58Ds.[52]

The OH-58A Kiowa is a 4-place observation helicopter. The Kiowa has two-place pilot seating, although the controls in the left seat are designed to be removed to carry a passenger up front. During its Vietnam development, it was fitted with the M134 Minigun, a 7.62 mm electrically operated machine gun. A total of 74 OH-58A helicopters were delivered to the Canadian Armed Forces as COH-58A and later redesignated as CH-136 Kiowa helicopters.[53]

In 1978, OH-58A aircraft began to be converted to the same engine and dynamic components as the OH-58C.[54] And, in 1992, 76 OH-58A were modified with another engine upgrade, a thermal imaging system, a communications package for law enforcement, enhanced navigational equipment and high skid gear as part of the Army National Guard's (ARNG) Counter-Drug RAID program.

The OH-58B was an export version for the Austrian Air Force.[55] The Australian Government also procured the OH-58A for the Australian Army and Royal Australian Navy as the CAC CA-32. Produced under contract in Australia by Commonwealth Aircraft Corporation, the CA-32 was the equivalent of the 206B-1 (upgraded engine and longer rotor blades). The first twelve of 56 were built in the U.S. then partially disassembled and shipped to Australia where they were reassembled.[56] Helicopters in the naval fleet were retired in 2000.[56]

Equipped with a more robust engine, the OH-58C was supposed to solve many issues and concerns regarding the Kiowa's power. In addition to the upgraded engine, the OH-58C had unique IR suppression systems mounted on its turbine exhaust. Early "C" models featured flat-panel windscreens as an attempt to reduce glint from the sun, which could give away the aircraft's location to an enemy. The windscreens had a negative effect of limiting the forward view of the crew, a previous strength of the original design.

The aircraft was also equipped with a larger instrument panel, roughly a third bigger than the OH-58A panel, which held larger flight instruments. The panel was also equipped with Night Vision Goggle (NVG) compatible cockpit lighting. The lights inside the aircraft are modified to prevent them from interfering with the aircrews' use of NVGs.[57] OH-58C aircraft were also the first U.S. Army scout helicopter to be equipped with the AN/APR-39 radar detector, a system which allowed the crew to know when there were anti-aircraft radar systems in proximity to the aircraft.[58]

Some OH-58C aircraft were armed with two AIM-92 Stingers. These aircraft are sometimes referred to as OH-58C/S, the "S" referring to the Stinger installation.[59] Called Air-To-Air Stinger (ATAS), the weapon system was intended to provide an air defense capability.

The OH-58D (Bell Model 406) was the result of the Army Helicopter Improvement Program (AHIP). An upgraded transmission and engine gave the aircraft the power it needed for nap-of-the-earth flight profiles, and a four-bladed main rotor made it much quieter than the two-bladed OH-58C. The OH-58D introduced the distinctive Mast-Mounted Sight (MMS) above the rotor system, and a mixed glass cockpit, with traditional instruments identified as "standby" for emergency use.

The Bell 406CS "Combat Scout" was based on the OH-58D (sometimes referred to as the MH-58D). Fifteen aircraft[7][60] were sold to Saudi Arabia.[61] A roof-mounted Saab HeliTOW sight system was opted for in place of the MMS.[62] The 406CS also had detachable weapon hardpoints on each side.

The AH-58D was an OH-58D version operated by Task Force 118 (4th Squadron, 17th Cavalry) and modified with armament in support of Operation Prime Chance. The weapons and fire control systems would become the basis for the Kiowa Warrior. AH-58D is not an official DOD aircraft designation, but is used by the Army in reference to these aircraft.[63][64][65]

The Kiowa Warrior, sometimes referred to by its acronym KW, is the armed version of the OH-58D Kiowa. The main difference that distinguishes the Kiowa Warrior from the original AHIP aircraft is a universal weapons pylon found mounted on both sides of the aircraft. These pylons are capable of carrying combinations of AGM-114 Hellfire missiles, air-to-air Stinger (ATAS) missiles, 7-shot 2.75 in (70 mm) Hydra-70 rocket pods,[66] and an M296 .50 caliber machine gun. The standard of performance for aerial gunnery from an OH-58D is to achieve at least one hit out of 70 shots fired at a wheeled vehicle 800 to 1,200 m (2,625 to 3,937 ft) away.[67][68] The Kiowa Warrior upgrade also includes improvements in available power, navigation, communication and survivability, as well as modifications to improve the aircraft's deployability.[69]

The OH-58F is the designation for an upgrade of the OH-58D. The Cockpit and Sensor Upgrade Program (CASUP) features a nose-mounted targeting and surveillance system in addition to the OH-58D's mast-mounted sensor. The AAS-53 Common Sensor Payload (CSP) includes an advanced infrared camera, color Electro-Optical camera, and image intensifier; it is expected to improve flight performance by 1-2% through weight and drag reductions.[70] Cockpit upgrades include the Control and Display Subsystem version 5, for more processing and storage power, three color multi-function displays, and dual-independent advanced moving maps. The OH-58F shall have Level 2 Manned-Unmanned (L2MUM) teaming, the Force Battle Command Brigade and Below (FBCB2) display screen, with future improvement to Blue Force Tracker 2. Survivability enhancements include ballistic floor armor and the Common Missile Warning System (CMWS). Other features include improved situational awareness, digital inter-cockpit communications, HELLFIRE future upgrades, redesigned wiring harness, Health and Usage Monitoring (HUMS), and enhanced weapons functionality via 1760 digital interface. It has a dual-channel, full-authority digital engine-controller to ensure operations at required power levels in all environments.[71][72][73] The OH-58F did not address engine power requirements; Rolls-Royce proposed adaptions of the Model 250-CR30 engine to increase output by 12%.[74]

In October 2012, the first OH-58F was finished. Unlike most military projects, the Army designed and built the new variant itself, which lowered developmental costs. It weighed 3,590 lb, 53 lb below the target weight and about 200 lb lighter than the OH-58D. The weight savings are attributed to more efficient wiring and a lighter sensor. The first production aircraft will start being built in January 2013 and will be handed over to the Army by the end of the year. Low rate production was to start in March 2015, with the first operational squadron being fully equipped by 2016. The Army is to buy 368 OH-58Fs, older A, C and D-model OH-58s were to be remanufactured into F-models.[75] Because of battle damage and combat attrition, total OH-58F numbers will be about 321 aircraft.[76] The first flight of the OH-58F occurred on 26 April 2013.[77]

The Army plans to retire its Kiowa fleet and end the F-model CASUP upgrades. CASUP and SLEP upgrades would cost $3 billion and $7 billion respectively, totaling $10 billion for features that the Army cannot afford to allocate money to. The OH-58D can reach 20 percent of armed aerial scout mission requirements, upgrading to OH-58F standard would raise that to 50 percent. Replacing the Kiowa with Apaches and unmanned systems in scout roles would meet 80 percent of requirements.[78] In the first quarter of 2014, Bell received a stop-work order for the Kiowa F-model CASUP program.[79]

On April 14, 2011, Bell performed the successful first flight of their OH-58F Block II variant. The Block II was Bell's entry in the Armed Aerial Scout program.[80] It built on the improvements of the F-model, and added features including the Honeywell HTS900 turboshaft engine, the transmission and main rotors of the Bell 407, and the tail and tail rotor of the Bell 427. Bell started voluntary flight demonstrations in October 2012, and the Army had to decide by December if it would even proceed with the AAS program.[81] Bell hoped for the Army to go with their service life extension models instead of the program. The F-model Kiowa is an "obsolescence upgrade," while the Block II was seen as the performance upgrade. This gave the Army flexibility in times of shrinking budgets, as they had the option of upgrading the Kiowa to the F-model and then continuing to the Block II later when there were sufficient funds.[82] Shortly before December 2012, the Army decided they would recommend proceeding with the AAS program.[44][45] The Army ended the AAS program in late 2013.[83] With the onset of sequestration budget cuts in early 2013, it was decided that the $16 billion cost of buying new armed scout helicopters was too expensive.[78]

The OH-58X was a modification of the fourth development OH-58D (s/n 69-16322) with partial stealth features and a chin-mounted McDonnell-Douglas Electronics Systems turret as a night piloting system; including a Kodak FLIR system with a 30-degree field of view. Avionics systems were consolidated and moved to the nose, making room for a passenger seat in the rear. No aircraft were produced.[2]

^The last new build aircraft were delivered to the U.S. Army in 1989. The subsequent arming of the AHIP and the System Safety Enhancement Program (SSEP) caused aircraft to be steadily refitted until 1999.

^See Light Observation Helicopter. The Navy, who was assisting the Army in the selection phase, recommended the Hiller Model 1100, while the Army team preferred the Bell D-250, and then the 1100. The Selection Board selected both aircraft. Afterwards, the acting Army Chief of Staff directed the Selection Board to include the Hughes 369 in the fly-off competition.

^Office of the Assistant Secretary of Defense (Public Affairs). "OH-58C Helicopter Down in North Korea". Press Release. United States Department of Defense. 19 December 1994. Accessed 30 December 2007.